Eef Hoos, 61, said he had spotted what appeared to be plain-clothes police officers taking photographs around his villa in a remote mountain region early this morning.

He told reporters that on visiting the local police headquarters he was quizzed about the disappearance of Madeleine, who vanished from the McCann family's rented apartment in the resort of Praia da Luz on May 3.

Mr Hoos said police wanted to inspect his backyard incinerator. This afternoon reporters saw two men in an unmarked car arrive at the villa, refusing to answer questions.

The men were police officers who took documents related to animal cremations and ordered Mr Hoos to attend the local police headquarters on Monday for more questions, he said.

Police had visited him "20 or 30" other times in connection with other matters, he said, adding that one policeman had asked him whether he had met Madeleine's parents.

"He asked me three times if I had spoken to the parents. I said I had not spoken to the parents. The other guy said he had seen that I had spoken to the parents. He said that he had heard that I had spoken to the parents of the girl," Mr Hoos said.

Mr Hoos, who served almost eight years in jail for planting bombs in the Netherlands in the 1980s, was first interviewed by police in July.

Gerry and Kate McCann today visited the London offices of their lawyers, Kingsley Napley.

Their spokesman, Clarence Mitchell, said the couple were "very encouraged" to hear that police have no plans to interview them again about their daughter's disappearance.

Mr Mitchell said the McCanns - whom Portuguese police named earlier this month as "arguidos", or official suspects, in the case - were relieved to be able to stay in the UK with their twins but were "more than happy" to return to Portugal if necessary. The pair vigorously deny any role in Madeleine's disappearance.

The Portuguese attorney general overseeing the investigation of the McCanns ruled yesterday that there was not enough evidence to justify their further questioning.

Mr Mitchell told GMTV: "This is positive news. This is encouraging. As the news came through from Portugal last night, I spoke to Gerry on the phone within minutes and ran him through the statement and it is now for the Portuguese lawyers acting on Gerry and Kate's behalf to assess this accurately, make sure the translations are sure.

"But the fact that they don't have to go back to be re-interviewed and that they can stay in England at the very heart of their family and support network, and the twins aren't disturbed any more, is good news and we see it as very encouraging."

The McCanns returned to their Leicestershire home 11 days ago from the Algarve resort where their daughter disappeared. Asked if it appeared that the police case was collapsing, Mr Mitchell said today: "That is for others to judge. Our role is to liaise with the Portuguese authorities fully.

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